[Numpy-discussion] Request for enhancement to numpy.random.shuffle
josef.pktd at gmail.com
josef.pktd at gmail.com
Sun Oct 12 11:59:44 EDT 2014
On Sun, Oct 12, 2014 at 11:33 AM, Warren Weckesser
<warren.weckesser at gmail.com> wrote:
>
>
> On Sun, Oct 12, 2014 at 11:20 AM, <josef.pktd at gmail.com> wrote:
>>
>> On Sun, Oct 12, 2014 at 10:54 AM, Warren Weckesser
>> <warren.weckesser at gmail.com> wrote:
>> >
>> >
>> > On Sun, Oct 12, 2014 at 7:57 AM, Robert Kern <robert.kern at gmail.com>
>> > wrote:
>> >>
>> >> On Sat, Oct 11, 2014 at 11:51 PM, Warren Weckesser
>> >> <warren.weckesser at gmail.com> wrote:
>> >>
>> >> > A small wart in this API is the meaning of
>> >> >
>> >> > shuffle(a, independent=False, axis=None)
>> >> >
>> >> > It could be argued that the correct behavior is to leave the
>> >> > array unchanged. (The current behavior can be interpreted as
>> >> > shuffling a 1-d sequence of monolithic blobs; the axis argument
>> >> > specifies which axis of the array corresponds to the
>> >> > sequence index. Then `axis=None` means the argument is
>> >> > a single monolithic blob, so there is nothing to shuffle.)
>> >> > Or an error could be raised.
>> >> >
>> >> > What do you think?
>> >>
>> >> It seems to me a perfectly good reason to have two methods instead of
>> >> one. I can't imagine when I wouldn't be using a literal True or False
>> >> for this, so it really should be two different methods.
>> >>
>> >
>> >
>> > I agree, and my first inclination was to propose a different method (and
>> > I
>> > had the bikeshedding conversation with myself about the name:
>> > "disarrange",
>> > "scramble", "disorder", "randomize", "ashuffle", some other variation of
>> > the
>> > word "shuffle", ...), but I figured the first thing folks would say is
>> > "Why
>> > not just add options to shuffle?" So, choose your battles and all that.
>> >
>> > What do other folks think of making a separate method?
>>
>> I'm not a fan of many similar functions.
>>
>> What's the difference between permute, shuffle and scramble?
>
>
>
> The difference between `shuffle` and the new method being proposed is
> explained in the first email in this thread.
> `np.random.permutation` with an array argument returns a shuffled copy of
> the array; it does not modify its argument. (It should also get an `axis`
> argument when `shuffle` gets an `axis` argument.)
>
>
>> And how do I find or remember which is which?
>
>
>
> You could start with `doc(np.random)` (or `np.random?` in ipython).
If you have to check the docstring each time, then there is something wrong.
In my opinion all docstrings should be read only once.
It's like a Windows program where the GUI menus are not **self-explanatory**.
What did Save-As do ?
Josef
>
> Warren
>
>
>>
>>
>>
>> >
>> >
>> >>
>> >> That said, I would just make the axis=None behavior the same for both
>> >> methods. axis=None does *not* mean "treat this like a single
>> >> monolithic blob" in any of the axis=-having methods; it means "flatten
>> >> the array and do the operation on the single flattened axis". I think
>> >> the latter behavior is a reasonable interpretation of axis=None for
>> >> both methods.
>> >
>> >
>> >
>> > Sounds good to me.
>>
>> +1 (since all the arguments have been already given
>>
>>
>> Josef
>> - Why does sort treat columns independently instead of sorting rows?
>> - because there is lexsort
>> - Oh, lexsort, I haven thought about it in 5 years. It's not even next
>> to sort in the pop up code completion
>>
>>
>> >
>> > Warren
>> >
>> >
>> >>
>> >>
>> >> --
>> >> Robert Kern
>> >> _______________________________________________
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>> >
>> >
>> >
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